Exchanging Substances Part 2- Digestion Flashcards
What is digestion
Breaking down large insoluble molecules into small soluble ones
So they can be absorbed into the bloodstream
- extracellular
What do the salivary glands do
Moisten food and begin digestion of maltose
What does the oesphegus do
Transports food to the stomach
What does the liver do
Produce bile
What does the gall bladder do
Stores and releases bile into the small intestine
- neutralise stomach acid (optimum ph for enzymes0
- emulsifies lipids to increase sa
What does the stomach do
Muscular tissue - mix up food
HCl, mucus, enzymes
Pepsin
Forms Chyme
What does the pancreas do
Release digestive enzymes
With intestinal wall- produce alkaline slats- keep ph neutral
What does the small intestine do
Breaks down food and absorbs nutrients
What does the large intestine do
Absorbs water and ions
What does the rectum do
Stores and expels faeces
What is the difference between chemical and physical digestion
Physical - break down of larger into small food peices
Chemical - carried out by enzymes - hydrolysases
What does amylase do and where is it stored
Breaks down starch into maltose (disaccharide )
Hydrolysis of glycosidic bonds
Made in salivary glands and pancreas
Salivary glands secrete amylase into the mouth where starch is hydrolysed
What does Maltase do
Maltose
Into 2 alpha glucose
What does sucrase do
Sucrose
Glucose and fructose
What is lactase for
Lactose
Glucose and galactose
Describe the trasport of lipids across membranes
The globule is emulsified by bile salts -> into small lipid droplets (mad eof monoglycerides and fatty acids)
These combine with bile slats to form micelles
These helps move monoglycerides and fatty acids towards the epithelium
Come into contact with cells. Micelles break down and monolgucerids, fatty acids diffuse across
One inside, monoglycerides and fatty acids are transport to the ER to recombine to form triglycerides
Continuing in the Golgi apparatus- triglycerides associate with cholesterol and lipoproteins called chylomicrons
Vesicles move two the cell membrane and move out by Exocytosis
- enter lymphatic capillaries called lacteals that are found at the centre of each villus
Chylomicrons pass into the bloodstream
How do micelles help with lipid absorbtion
Make fatty acids more soluble in water
Carry fatty acids to the epithelial cells/ lining of ileum
Maintain higher concentration of fatty acids to cell
Fatty acids absorbed by diffusion
Micelles include bile salts and fatty acid s
What is a chylomicrons
Triglyceride
+ cholesterol, + lipoprotein
What does protease do
Breaks down protein into amino acids
Hydrolysising peptide bonds
What re the differences between exo, endo and di peptidases
Endopeptidase act in the middle of protein/polypeptide
OR
Endopeptidase produces short(er) polypeptides/ increase number of ends
Exopeptidases act at end of protein/polypeptide
OR
Exopeptidase produces dipeptides/amino acids.
Dipeptidase acts on dipeptide/between two amino acids
OR
Dipeptidase produces (single) amino acids:
What are the adaptations of th ileum for diffusion
Villi - large sa
Villi epithelium - Single layer - short diffusion
Muscle in villi- conc. gradient
Good blood supply
